NHC-Stabilised Parent Tripentelyltrielanes

A missing family of the extremely air sensitive tripentelyltrielanes was discovered. Their stabilisation was achieved by using the bulky NHC IDipp (NHC=N-heterocyclic carbene, IDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene). The tripentelylgallanes and tripentelylalanes IDipp ⋅ Ga(PH₂ )₃ (1 a), IDipp ⋅ Ga(AsH₂ )₃ (1 b), IDipp ⋅ Al(PH₂ )₃ (2 a) and IDipp ⋅ Al(AsH₂ )₃ (2 b) were synthesised by salt metathesis of IDipp ⋅ ECl₃ (E=Al, Ga, In) with alkali metal pnictogenides such as NaPH₂ /LiPH₂ ⋅ DME and KAsH₂ , respectively. Moreover, the detection of the first NHC-stabilised tripentelylindiumane IDipp ⋅ In(PH₂ )₃ (3) was possible by multinuclear NMR spectroscopy. Initial investigations of the coordination ability of these compounds resulted in the successful isolation of the coordination compound [IDipp ⋅ Ga(PH₂ )₂ (μ₃ -PH₂ {HgC₆ F₄ }₃ )] (4) by reaction of 1 a with (HgC₆ F₄ )₃ . The compounds were characterised by multinuclear NMR spectroscopy as well as single crystal X-ray diffraction studies. Supporting computational studies highlight the electronic features of the products.

NHC-stabilized Parent Arsanylalanes and -gallanes

The synthesis and characterization of the unprecedented compounds IDipp⋅E'H2 AsH2 (E'=Al, Ga; IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) are reported, the first monomeric, parent representatives of an arsanylalane and arsanylgallane, respectively, stabilized only by a LB (LB=Lewis Base). They are prepared by a salt metathesis reaction of KAsH2 with IDipp⋅E'H2 Cl (E'=Al, Ga). The H2 -elimination pathway through the reaction of AsH3 with IDipp⋅E'H3 (E'=Al, Ga) was found to be a possible synthetic route with some disadvantages compared to the salt metathesis reaction. The corresponding organo-substituted compounds IDipp⋅GaH2 AsPh2 (1) and IDipp⋅AlH2 AsPh2 (2) were obtained by the reaction of KAsPh2 with IDipp⋅E'H2 Cl (E'=Al, Ga). The novel branched parent compounds IDipp⋅E'H(EH2 )2 (E'=Al, Ga; E=P, As) were synthesized by salt metathesis reactions starting from IDipp⋅E'HCl2 (E'=Al, Ga). Supporting DFT computations give insight into the different synthetic pathways and the stability of the products.

Phosphanylalanes and Phosphanylgallanes Stabilized only by a Lewis Base

The synthesis and characterization of the first parent phosphanylalane and phosphanylgallane stabilized only by a Lewis base (LB) are reported. The corresponding substituted compounds, such as IDipp⋅GaH2 PCy2 (1) (IDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene) were obtained by the reaction of LiPCy2 with IDipp⋅GaH2 Cl. However, the LB-stabilized parent compounds IDipp⋅GaH2 PH2 (3) and IDipp⋅AlH2 PH2 (4) were prepared via a salt metathesis of LiPH2 ⋅DME with IDipp⋅E'H2 Cl (E'=Ga, Al) or by H2 -elimination reactions of IDipp⋅E'H3 (E'=Ga, Al) and PH3 , respectively. The compounds could be isolated as crystalline solids and completely characterized. Supporting DFT computations gave insight into the reaction pathways as well as into the stability of these compounds with respect to their decomposition behavior.